Ryanair bosses have reportedly written to pilots asking them to choose between unpaid leave or a transfer in a warning that could otherwise mean they join the 9,000 job losses at Thomas Cook.
The airline - run by billionaire Michael O'Leary - issued to memo to workers in the 24 hours after the firm's collapse, advising them on why they need to take up opportunities at other bases abroad.
It told his crews that a "significant surplus of pilots must be reduced" at UK bases including Stansted and Manchester, and encouraged them to take 12 months of unpaid leave.
It said that there were limited vacancies for full-time pilots at bases in Morocco, Romania and Hungary.
The memo, sent on Tuesday, said: "With yesterday’s collapse of Thomas Cook with the loss of 9,000 jobs in the UK and potentially a further 13,000 jobs across Europe, we hope that there will be sufficient applications for unpaid leave/part time, so we do not have to resort to job losses at [your base] this winter."
It blamed the delay to Boeing 737 Max deliveries for the decision. Ryanair had ordered up to 135 of the aircraft for its expansion plans, with the first planes due this year.
The model remains grounded, however, since the Ethiopian Airlines and Lion Air crashes.
The airline, which reported profits of €1billion (£886million) in May, issued the warning a week after UK pilots called off the remainder of strikes this month.
The pilots union, Balpa, had complained about Ryanair’s "abysmal approach to industrial relations" and said the dispute over pay and conditions was driven by resentment over a range of cost-saving measures used by Ryanair.
Ryanair had called the strikes pointless and managed to operate the majority of its UK schedules by bringing in more contractors and pilots from overseas bases. The airline had warned of winter base closures across Europe.
Last week, the chief executive, Michael O’Leary, was awarded a new pay package in which he could receive a €99m (£88m) bonus within five years, although almost half of Ryanair shareholders voted against it.
